Monitoring systems (antitheft systems) for monitoring a vehicle to prevent theft have been developed to this day. Such a monitoring system is, for instance, arranged in such a manner that, a vibration sensor is attached to a vehicle, and when vibration of the vehicle is sensed, it is assumed that someone is preparing theft (preparations for theft), so that a warning such as blowing a horn is performed.
However, only the result of sensing by the vibration sensor is usually not enough to precisely determines whether the vehicle is vibrating due to the preparations for theft or the vehicle is vibrating due to other reasons. For this reason, warnings are frequently performed by mistake. Conceivable reasons of the vibration of a vehicle other than the preparations for theft are such as an earthquake and construction works. In this wise, a monitoring system which is likely to perform mistaken warnings is untrustworthy.
There is a method in view of the problem above, which is arranged such that a determination is made in consideration of information other than the information from the vibration sensor of the vehicle. For instance, in regard to earthquake, there are institutions for collecting information regarding vibration caused by extensive earthquakes, so that the determination can be made in consideration of the vibration caused by the earthquake, when the information can be obtained from the institutions.
Also, there is another method disclosed by, for instance, Japanese Laid-Open Patent Application No. 2000-348263 (Tokukai 2000-348263; published on Dec. 15, 2000), for determining whether or not a vibration is attributed to an act of thievery (preparations for theft), on ground of an waveform of the vibration sensed by a sensor (vibration sensor).
However, even if such a method that takes the information from the institutions into consideration can determine whether or not a vibration is attributed to an earthquake, other types of information concerning, for instance, an abnormal vibration in a parking lot where the car is left, a vibration due to construction works, and an influence of local wind are hardly obtainable from the institutions, thereby being hardly taken into consideration.
Furthermore, according to the determining method on ground of the waveform of a vibration, there could be a case that it is hardly determinable whether or not the vibration is due to preparations for theft.
In this manner, since conventional arts cannot steadily deliver precise determinations, it has been demanded to further improve the precision of determinations.
The present invention is done to solve the problem above, and thus the objective of the present invention is to provide a monitoring system, central monitoring apparatus, and on-board monitoring apparatus, which can reduce the possibility of misidentifying a vibration, which is of no concern with preparations for theft, as a vibration due to preparations for theft.